Thoughts on Hotmail filtering


One of the new bits of information to come out of the EEC15 deliverability discussions is how Hotmail is looking at engagement differently than other webmail providers.
Many webmail providers really do look at overall engagement with a mail when making delivery decisions. And this really impacts new subscribers the most. If there is a mailing where a lot of subscribers are engaged, then new subscribers will see the mail in their inbox. Based on what was said at the webinar earlier this week engagement has no effect at Hotmail outside of the individual user’s box.
I’ve certainly seen this with clients who’ve tried trimming subscriber lists but that doesn’t really help get mail moved from the Hotmail bulk folder to the inbox.
Instead of subscriber lists, Hotmail is really looking at bounces. They’re watching the number of nonexistent accounts senders are mailing to and they’re counting and a sender hits too many bad addresses and that is a major hit to their reputation.
All of this makes remediation at Hotmail challenging. Right now, we can remediate a bad reputation at a lot of ISPs and the filters catch up and mail starts flowing back to the inbox. Hotmail has set up a system that they say is “hard for spammers to game.” This seems to translate into hard for legitimate senders to fix their reputation.
Hotmail is, IMO, the current tough nut in terms of deliverability. Develop a bad reputation there and it’s difficult to fix it. I’m sure it’s possible, though.

About the author


This site uses Akismet to reduce spam. Learn how your comment data is processed.

  • Hotmail and Gmail are usually the two I find myself having to help clients with. I know what was said by Hotmail at EEC15 and this week’s webinar follow-up, but I still find cutting the list and removing the inactives tends to fix things.

  • Hotmail/’s email filtering is based upon numerous things:
    – Machine learning
    – User junk reports (clicking “This is spam”)
    – Their feedback loop program (used to train machine learning)
    – IP reputation
    – Sender reputation
    – User mailbox settings
    – And a few other spam filter settings
    The filter is nearly entirely automated; it’s the only way to make it scale. In general, if email from bulk senders isn’t getting through it’s usually because lots of users have been marking it as spam.
    Remediation is through the SNDS portal. You have to prove IP ownership but once you do, you can get reports of how users are treating your email. It’s true that it is “hard for spammers to game” because spammers have tried to game it (and continue to) and so the system has clamped down to look at multiple pieces of information before making a decision, and user junk complaints help with it.

By laura

Recent Posts


Follow Us